[JS]

First, do you run rubber brake lines or stainless?
Second, has the car sit or is the brake fluid old?

Reason, my friends Posche had been sitting for awhile and the brake fluid actcually cause the rubber brake line to swell from the inside so that fluid would flow to the caliper, but not back once the brake was reliesed. The hotter it got, stop and go traffic, the worse the brakes dragged. (drug?) Kind of similar to clogged arteries around your heart for a comparison.

If you think you brake lines are bad, take one off and try to blow compressed air through it. With the Porsche line, you could barely feel the air coming out it was so bad.

Anyway, the new brake fluids that the racers use won't go bad like regular brake fluid if it sits too long. Going to stainless line will cure it too.